Thermal Monitoring of Leakage Through Dams

The technique involves very accurate temperature measurement at shallow depth below the reach of the surface diurnal cycle. Temperatures respond to subsurface water movement (with advective heat transfer) acting as a heat source or heat sink from which conductive heat transfer changes the temperatures of the overlying and surrounding materials and attenuates the amplitude and phase of the ambient annual temperature wave. Variables include velocity and depth of the moving fluid, its source temperature and changes of source temperature through time as related to changes in reservoir head; the nature of the embankment and its foundation and abutments; the nature of materials through which heat is transferred overlying the leakage zone; and local climatic factors.